It is known for a drive system for an electric or hybrid vehicle to have an engine (e.g., internal combustion engine), a generator coupled to the engine, a Direct Current (DC) bus, and a motor. The DC bus is coupled electrically between the generator and the motor to drive one or more elements of the vehicle. A converter is coupled electrically between the generator and the DC bus and is controlled to convert Alternating Current (AC) power into DC power during generating of the generator and DC power into AC power during motoring of the motor. The motor can be a Switched Reluctance (SR) motor, a Permanent Magnet (PM) AC Motor or an Induction AC Motor.
In an inverter-fed drive system, a power inverter is coupled electrically between the DC bus and the motor and is controlled to convert DC power from the DC bus into AC power during motoring of the motor and to convert AC power into DC power during electric braking of the motor. In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in batteries. A voltage sensor is coupled electrically to the DC bus to sense a DC bus voltage and output a DC bus voltage signal indicative thereof. A current sensor senses a phase current of the motor and outputs a phase current signal indicative thereof. A control system is coupled electrically to the voltage sensor and the current sensor to receive signals from the sensors pertaining to system operation.
In an inverter-fed electric drive system, it can be appreciated that a variety of failures can occur in the various power and control components used in the systems, such as, Insulated Gate Bi-polar Transistors (IGBTs) in the inverters, diodes in the inverters, electric machines, motor windings, dc bus capacitors, power cables between inverters and electric machines, etc.